1. Technical Field
This disclosure relates to computer display systems, and more particularly to power management and bus scheduling.
2. Description of the Related Art
Digital systems of various types often include, or are connected to, a display for the user to interact with the device. The display may be external or it may be incorporated into the device. The display provides a visual interface that the user can view to interact with the system and applications executing on the system. In some cases (e.g., touchscreens), the display also provides a user interface to input to the system.
Modern display devices have evolved from cathode ray tubes that used electron guns to illuminate phosphor-coated screens by scanning across the screen horizontally from one side to the other and vertically from top to bottom in a raster to display a frame of information. When the beam reached the bottom of the screen, it needed time to start a new frame at the top. This time interval is referred to as the vertical blanking interval (VBI). During the VBI received data is not actually displayed. Modern displays have no need of the VBI, but display processing components still provide it for backward compatibility. Accordingly, because data is not displayed during the VBI, some display components take advantage of this time period and may go to an inactive state to save power. However, in many conventional low power systems, additional power reductions may be forfeited due to lack of coordination between display components and other system components.